Digital servo track format

Abstract

A digital servo track pattern for a magnetic medium which can be recorded and reproduced by a recording and reproducing system. The servo track pattern has a plurality of digital mark patterns recorded thereon, each of said digital mark patterns having a leading identifier field of digital bits, a trailing identifier field of digital bits and a field of digital synchronizing data located between said leading and trailing identifier fields. The leading identifier field of digital bits is electrically equivalent during reproducing while the medium is moving in a first direction to the trailing identifier field of digital bits while the medium is moving in a direction opposite to said first direction.

What is claimed is: 
     
       1. A longitudinal servo track pattern located on an elongated medium having other areas on which information are recorded and reproduced, said servo track pattern adapted to provide signals for a servo system for controlling the movement of the medium in one of two directions, said servo track pattern comprising a plurality of digital mark patterns recorded thereon, each of said digital mark patterns comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields, said synchronizing data field configured to determine the direction of tape motion during reproducing,   wherein each of said leading and trailing identifier fields comprises a predetermined number of bits, said field of digital synchronizing data having a length that is equal to the length of each of said identifier fields.   
     
     
       2. A longitudinal servo track pattern as defined in claim 1 wherein said predetermined number of bits in each of said identifier fields is four. 
     
     
       3. A longitudinal servo track pattern as defined in claim 1 wherein said synchronizing data comprises the ANSI sync word. 
     
     
       4. A longitudinal servo track pattern located on an elongated medium having other areas on which information are recorded and reproduced, said servo track pattern comprising a plurality of digital mark patterns recorded thereon, each of said digital mark patterns comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields,   wherein each of said leading identifier field and said trailing identifier field comprises a plurality of bits of digital data, and wherein the flux transition directions and locations of said bits in a first direction are predefined,   further wherein the locations of successive flux transitions in said trailing identifier field from an opposite direction to said first direction are identical to the locations of successive transitions of said leading identifier field transitions in said first direction, the direction of each successive flux transition of said trailing identifier field in said second direction being opposite the direction of each successive flux transition in said leading identifier field from said first direction; and   wherein said synchronizing data comprises a first half of flux transition directions and locations in said first direction, and a second half of flux transition directions and locations, said locations and directions of successive flux transitions in the opposite direction of said first direction of said second half being identical to the locations of flux transitions of said first half in said first direction, the direction of successive flux transitions of said first half in said first direction being opposite the direction of successive flux transitions of said second half in said opposite direction.   
     
     
       5. A longitudinal servo track pattern as defined in claim 4 wherein said synchronizing data has a length equal to four bits of digital information. 
     
     
       6. A longitudinal servo track pattern as defined in claim 4 wherein a servo mark consists of a flux transition located at the end of said first half and the beginning of said second half of said synchronizing data. 
     
     
       7. A longitudinal servo track pattern located on an elongated medium having other areas on which information are recorded and reproduced, said servo track pattern comprising a plurality of digital mark patterns recorded thereon, each of said digital mark patterns comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields,   wherein the magnetic tape has an area in which information are recorded on helical tracks, one of said digital mark patterns being recorded for each pair of helical tracks.   
     
     
       8. A longitudinal servo track pattern as defined in claim 7 wherein units of information of a predetermined minimum size are recorded on a predetermined number of successive helical tracks, each said mark pattern having a leading identifier field that uniquely identifies the helical track pair of the beginning of each unit and a leading identifier field that uniquely identifies the middle helical track pair of each unit, and leading identifier fields that uniquely identify all other helical track pairs as not being beginning and middle helical track pairs. 
     
     
       9. A longitudinal servo track pattern as defined in claim 8 wherein each of said units of information comprises approximately 1.2 Megabytes. 
     
     
       10. A longitudinal servo track pattern as defined in claim 8 wherein each of said leading identifier fields which uniquely identify the beginning helical track pair, the middle helical track pair and all other helical track pairs comprise bit patterns that are different from one another. 
     
     
       11. A longitudinal servo track pattern as defined in claim 8 wherein said predetermined number of successive helical tracks is 32 helical tracks. 
     
     
       12. A longitudinal servo track pattern as defined in claim 10 wherein said bit pattern for said leading identifier field which uniquely identifies the beginning helical track pair is one of 1001 and 1111, with the bit pattern of successive units alternating between the two bit patterns. 
     
     
       13. A longitudinal servo track pattern as defined in claim 10 wherein said bit pattern for said leading identifier field which uniquely identifies the middle helical track pair is 0011. 
     
     
       14. A longitudinal servo track pattern as defined in claim 10 wherein said bit pattern for said leading identifier field which uniquely identifies the all helical track pairs which are not beginning or middle helical track pairs is 0101. 
     
     
       15. A digitally recorded longitudinal servo track pattern for an elongated magnetic recording medium of the type which has separate recordable and reproducible areas, said servo track pattern being adapted to provide signals for a servo system for controlling the movement of the medium, the servo system having a magnetic reproducing head adapted to read the digitally recorded longitudinal servo track pattern during movement of the medium in either direction, said servo track pattern comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields;   said leading identifier field of digital bits being electrically equivalent during reproducing while the medium is moving in a first direction to the trailing identifier field of digital bits while the medium is moving in a direction opposite to said first direction,   wherein said field of synchronizing data comprises two halves, said first half being electrically equivalent during reproducing while the medium is moving in said first direction to said second half while the medium is moving in said opposite direction.   
     
     
       16. A digitally recorded longitudinal servo track pattern for an elongated magnetic recording medium of the type which has separate recordable and reproducible areas, said servo track pattern being adapted to provide signals for a servo system for controlling the movement of the medium, the servo system having a magnetic reproducing head adapted to read the digitally recorded longitudinal servo track pattern during movement of the medium in either direction, said servo track pattern comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields;   said leading identifier field of digital bits being electrically equivalent during reproducing while the medium is moving in a first direction to the trailing identifier field of digital bits while the medium is moving in a direction opposite to said first direction,   wherein each of said leading identifier field and said trailing identifier field comprises a plurality of bits of digital data, and wherein the flux transition directions and locations of said bits in a first direction are predefined,   wherein the locations of successive flux transitions in said trailing identifier field from an opposite direction to said first direction are identical to the locations of successive transitions of said leading identifier field transitions in said first direction, the direction of each successive flux transition of said trailing identifier field in said second direction being opposite the direction of each successive flux transition in said leading identifier field from said first direction,   wherein said plurality of bits in each of said identifier fields is four.   
     
     
       17. A digitally recorded longitudinal servo track pattern for an elongated magnetic recording medium of the type which has separate recordable and reproducible areas, said servo track pattern being adapted to provide signals for a servo system for controlling the movement of the medium, the servo system having a magnetic reproducing head adapted to read the digitally recorded longitudinal servo track pattern during movement of the medium in either direction, said servo track pattern comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields;   said leading identifier field of digital bits being electrically equivalent during reproducing while the medium is moving in a first direction to the trailing identifier field of digital bits while the medium is moving in a direction opposite to said first direction,   wherein each of said leading identifier field and said trailing identifier field comprises a plurality of bits of digital data, and wherein the flux transition directions and locations of said bits in a first direction are predefined,   wherein the locations of successive flux transitions in said trailing identifier field from an opposite direction to said first direction are identical to the locations of successive transitions of said leading identifier field transitions in said first direction, the direction of each successive flux transition of said trailing identifier field in said second direction being opposite the direction of each successive flux transition in said leading identifier field from said first direction,   wherein said synchronizing data comprises the ANSI sync word.   
     
     
       18. A digitally recorded longitudinal servo track pattern for an elongated magnetic recording medium of the type which has separate recordable and reproducible areas, said servo track pattern being adapted to provide signals for a servo system for controlling the movement of the medium, the servo system having a magnetic reproducing head adapted to read the digitally recorded longitudinal servo track pattern during movement of the medium in either direction, said servo track pattern comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields;   said leading identifier field of digital bits being electrically equivalent during reproducing while the medium is moving in a first direction to the trailing identifier field of digital bits while the medium is moving in a direction opposite to said first direction,   wherein each of said leading identifier field and said trailing identifier field comprises a plurality of bits of digital data, and wherein the flux transition directions and locations of said bits in a first direction are predefined,   wherein the locations of successive flux transitions in said trailing identifier field from an opposite direction to said first direction are identical to the locations of successive transitions of said leading identifier field transitions in said first direction, the direction of each successive flux transition of said trailing identifier field in said second direction being opposite the direction of each successive flux transition in said leading identifier field from said first direction,   wherein said synchronizing data comprises a first half of flux transition directions and locations in a first direction, and a second half of flux transition directions and locations, said locations and directions of successive flux transitions in the opposite direction of said first direction of said second half being identical to the locations of flux transitions of said first half in said first direction, the direction of successive flux transitions of said first half in the first direction being opposite the direction of successive flux transitions of said second half in said opposite direction.   
     
     
       19. A servo track pattern as defined in claim 18 wherein said synchronizing data has a length equal to four bits of digital information. 
     
     
       20. A digital mark pattern for a longitudinal track of a magnetic recording tape of the type which has other areas adapted to have data recorded thereon and reproduced therefrom, the longitudinal track providing servo information for a servo control system that is adapted to control the movement of the tape, said mark pattern comprising: a leading servo mark identifier field of digital data;   a trailing servo mark identifier field of digital data; and   a field of digital synchronizing data located between said leading and trailing servo mark identifier fields,   wherein each of said leading identifier field and trailing identifier field comprises a plurality of bits of digital data, and wherein the flux transition directions and locations of said bits in a first direction are predefined,   wherein the locations of successive flux transitions in said trailing identifier field from an opposite direction to said first direction are identical to the locations of successive transitions of said leading identifier field transitions in said first direction, the direction of each successive flux transition of said trailing identifier field in said second direction being opposite the direction of each successive flux transition in said leading identifier field from said first direction,   wherein said plurality of bits in each of said identifier fields is four.   
     
     
       21. A digital mark pattern for a longitudinal track of a magnetic recording tape of the type which has other areas adapted to have data recorded thereon and reproduced therefrom, the longitudinal track providing servo information for a servo control system that is adapted to control the movement of the tape, said mark pattern comprising: a leading servo mark identifier field of digital data;   a trailing servo mark identifier field of digital data; and   a field of digital synchronizing data located between said leading and trailing servo mark identifier fields,   wherein each of said leading identifier field and trailing identifier field comprises a plurality of bits of digital data, and wherein the flux transition directions and locations of said bits in a first direction are predefined,   wherein the locations of successive flux transitions in said trailing identifier field from an opposite direction to said first direction are identical to the locations of successive transitions of said leading identifier field transitions in said first direction, the direction of each successive flux transition of said trailing identifier field in said second direction being opposite the direction of each successive flux transition in said leading identifier field from said first direction,   wherein said synchronizing data comprises the ANSI sync word.   
     
     
       22. A digital mark pattern for a longitudinal track of a magnetic recording tape of the type which has other areas adapted to have data recorded thereon and reproduced therefrom, the longitudinal track providing servo information for a servo control system that is adapted to control the movement of the tape, said mark pattern comprising: a leading servo mark identifier field of digital data;   a trailing servo mark identifier field of digital data; and   a field of digital synchronizing data located between said leading and trailing servo mark identifier fields,   wherein each of said leading identifier field and trailing identifier field comprises a plurality of bits of digital data, and wherein the flux transition directions and locations of said bits in a first direction are predefined,   wherein the locations of successive flux transitions in said trailing identifier field from an opposite direction to said first direction are identical to the locations of successive transitions of said leading identifier field transitions in said first direction, the direction of each successive flux transition of said trailing identifier field in said second direction being opposite the direction of each successive flux transition in said leading identifier field from said first direction,   wherein said synchronizing data comprises a first half of flux transition directions and locations in a first direction, and a second half of flux transition directions and locations, said locations and directions of successive flux transitions in the opposite direction of said first direction of said second half being identical to the locations of flux transitions of said first half in said first direction, the direction of successive flux transitions of said first half in the first direction being opposite the direction of successive flux transitions of said second half in said opposite direction.   
     
     
       23. A digital mark pattern as defined in claim 22 wherein said synchronizing data has a length equal to four bits of digital information. 
     
     
       24. A digital mark pattern as defined in claim 22 wherein a servo mark consists of a flux transition located at the end of said first half and the beginning of said second half of said synchronizing data. 
     
     
       25. A digital mark pattern for a longitudinal track of a magnetic recording tape of the type which has other areas adapted to have data recorded thereon and reproduced therefrom, the longitudinal track providing servo information for a servo control system that is adapted to control the movement of the tape, said mark pattern comprising: a leading servo mark identifier field of digital data;   a trailing servo mark identifier field of digital data; and   a field of digital synchronizing data located between said leading and trailing servo mark identifier fields,   wherein the magnetic tape has an area in which information are recorded on helical tracks, one of said mark patterns being recorded for each pair of helical tracks.   
     
     
       26. A digital mark pattern as defined in claim 25 wherein units of information of a predetermined minimum size are recorded on a predetermined number of successive helical tracks, each said mark pattern having a leading servo mark identifier field that uniquely identifies the helical track pair of the beginning of each unit and a leading servo mark identifier field that uniquely identifies the middle helical track pair of each unit, and leading servo mark identifier fields that uniquely identify all other helical track pairs as not being beginning and middle helical track pairs. 
     
     
       27. A longitudinal servo track pattern as defined in claim 26 wherein each of said units of information comprises approximately 1.2 Megabytes. 
     
     
       28. A digital mark pattern as defined in claim 26 wherein each of said leading servo mark identifier fields which uniquely identify the beginning helical track pair, the middle helical track pair and all other helical track pairs comprise bit patterns that are different from one another. 
     
     
       29. A digital mark pattern as defined in claim 26 wherein said predetermined number of successive helical tracks is 32 helical tracks. 
     
     
       30. A digital mark pattern as defined in claim 28 wherein said bit pattern for said leading servo mark identifier field which uniquely identifies the beginning helical track pair is one of 1001 and 1111, with the bit pattern of successive units alternating between the two bit patterns. 
     
     
       31. A digital mark pattern as defined in claim 28 wherein said bit pattern for said leading servo mark identifier field which uniquely identifies the middle helical track pair is 0011. 
     
     
       32. A digital mark pattern as defined in claim 28 wherein said bit pattern for said leading servo mark identifier field which uniquely identifies the all helical track pairs which are not beginning or middle helical track pairs is 0101. 
     
     
       33. A digitally recorded longitudinal servo track pattern for an elongated magnetic recording medium of the type which has separate recordable and reproducable areas, said servo track pattern adapted to provide signals for a servo system for controlling the movement of the medium, the servo system having a magnetic reproducing head adapted to read the digitally recorded longitudinal servo track pattern during movement of the medium in one of two directions, said servo track pattern comprising: a leading identifier field of digital bits;   a trailing identifier field of digital bits; and   a field of digital synchronizing data located between said leading and trailing identifier fields, said field of digital synchronizing data comprising first and second halves,   wherein, during reproduction, said leading identifier field of digital bits is electrically equivalent, while the medium is moving in a first direction, to said trailing identifier field of digital bits, while the medium is moving in a second direction opposite to said first direction, and   wherein, during reproduction, said first half of said digital synchronizing data is electrically equivalent, while the medium is moving in said first direction, to said second half of digital synchronizing data, while the medium is moving in said opposite second direction.